It's getting closer.
Homura just stands there, watching the shadow swallow up everything in its path. Uprooted trees and debris fly overhead. Buildings disappear. It's getting closer...
"So, you're really going to do it." Kyuubey watches her, perched where the rising water can't touch him. "Humans never were creatures of logic, I suppose. You could barely make a scratch on Walpurgis; how can you hope to defeat the witch who took her place?"
"...I don't."
Out of the corner of her eye, she sees Kyuubey fade from view just before it hits. Suddenly, she's weightless, being sucked towards the outstretched arms of Kriemhild Gretchen at breakneck speeds.
Madoka, I'm sorry. I couldn't keep our promise. But I'm coming now. Let's be together this time.
The barrier opens up before her, and Homura practically feels her heart stop.
"Is...is this...?"
The sky is streaked with rainbows, and the ground is made of fluffy clouds, but it's unmistakably Mitakihara. She's standing before Madoka's house, which gives off an almost blinding gleam in the sun.
It's empty. So is the school. So is the mall. So is the arcade. Even though she saw the bodies of others rising into the witch's embrace, there's no people. No familiars. No witch.
Madoka, where are you? Please, don't leave me alone. I can't do it anymore. I've watched everyone die so many times. You keep slipping through my fingers. It hurts. I'm scared. You don't recognize me when we meet. We can be together here, right?
There's no answer. And that's when she realizes.
She made her wish for Madoka, for one person. That's why she wouldn't have minded staying in this barrier. She didn't need anybody else.
But Madoka needs everybody else. Her family, her teachers, her friends – even the people she passes on the sidewalk during the day. That's why this world, this 'heaven' born from her grief, has none of them in it. Madoka needs Homura to make sure it doesn't happen.
Homura readies her shield.
I'm sorry. That was stupid of me. I'll go back again. I'll help you escape. Because you don't deserve a world as empty and sad as this.
As everything disappears into the white whirl of time, she hears, very faintly: Thank you.